Metal matrix composite vehicle component and method

ABSTRACT

An exemplary method for making a metal matrix composite vented brake rotor includes: providing a first side plate; providing a second side plate; and welding the first and second side plates together. The first and second side plates have outer surfaces, inner surfaces, and metal matrix composite portions extending from the outer surfaces to a distance from the inner surface that is less than a thickness measured between the inner surface and outer surface. The inner surface of the first side plate includes a vent portion. The step of welding includes welding the first vent portion to the second inner surface to form the vented brake rotor, the vented brake rotor having a plurality of vents formed by the first and second inner surfaces and the first vent portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 15/397,446, filed Jan. 1, 2017, which claims thebenefit of U.S. Provisional Application Ser. No. 62/273,683, filed onDec. 31, 2015, titled VENTED METAL MATRIX COMPOSITE BRAKE ROTOR ANDMETHOD, the disclosure of which is incorporated herein by reference inits entirety.

TECHNICAL FIELD

The present application relates generally to methods of making metalmatrix composite vehicle components, and more specifically to methods ofmaking metal matrix composite vented brake rotors.

BACKGROUND OF THE INVENTION

A metal matrix composite (MMC) is generally made by incorporating areinforcing material into a metal matrix. For example, a MMC maycomprise a ceramic preform that is infiltrated with a metal. A MMCgenerally has properties and physical characteristics different frommetal that may be desirable depending on the application. For example,relative to the metal surrounding an MMC, the MMC may have higherspecific strength, a higher Young's modulus, higher temperatureresistance, higher transverse stiffness and strength, higher resistanceto moisture absorption, higher electrical and thermal conductivity,lower density, and higher wear resistance. The particular physicalproperties of MMCs are often dependent on the final application and maybe modified by changes in both the matrix and metal alloy used.

Vehicles often include disc brakes. A disc brake generally comprises arotating brake rotor. Calipers having brake pads that squeeze theexterior and interior of the brake rotor to cause friction and reducethe rotation of the brake rotor. During the vehicle braking processthere is often a high energy transfer to the frictional surface of thebrake rotor which can lead to a rise in temperature.

SUMMARY

Exemplary embodiments of methods of making vehicle components such asvented brake rotors are disclosed herein.

An exemplary method for making a metal matrix composite vented brakerotor includes: providing a first side plate; providing a second sideplate; and welding the first and second side plates together. The firstand second side plates have outer surfaces, inner surfaces, and metalmatrix composite portions extending from the outer surfaces to adistance from the inner surface that is less than a thickness measuredbetween the inner surface and outer surface. The inner surface of thefirst side plate includes a vent portion. The step of welding includeswelding the first vent portion to the second inner surface to form thevented brake rotor, the vented brake rotor having a plurality of ventsformed by the first and second inner surfaces and the first ventportion.

Another exemplary embodiment of the present disclosure relates to amethod for making a metal matrix composite vented brake rotor havingmetal matrix composite wear surfaces, the method including: preparing aceramic compound having reinforcing fibers and ceramic particles;forming first and second ceramic preforms from the ceramic compound;forming first and second metal matrix composite brake components byinfiltrating the first and second ceramic preforms with molten metal;and welding the first and second side plates together. The first andsecond metal matrix composite brake components have outer surfaces,inner surfaces, and metal matrix composite portions extending from theouter surfaces to a distance from the inner surface that is less than athickness measured between the inner surface and outer surface. Theinner surface of the first metal matrix composite brake componentincludes a vent portion. The step of welding includes welding the firstvent portion to the second inner surface to form the vented brake rotor,the vented brake rotor having a plurality of vents formed by the firstand second inner surfaces and the first vent portion.

Still another exemplary embodiment of the present disclosure relates toa method for making a metal matrix composite vehicle component havinglocalized metal matrix composite portions, the method including:providing a first vehicle component having a first metal matrixcomposite portion and a first metal portion that is substantially freefrom metal matrix composite material; providing a second vehiclecomponent having a second metal matrix composite portion and a secondmetal portion that is substantially free from metal matrix compositematerial; and welding the first and second metal portions together toform the metal matrix composite vehicle component

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention willbecome better understood with regard to the following description andaccompanying drawings in which:

FIG. 1 is a perspective view of a vented brake rotor;

FIG. 2 is a perspective view of the vented brake rotor of FIG. 1 with aportion of one of the rotor plates removed to expose the vents;

FIG. 3 is a cross-section view of the vented brake rotor of FIG. 1 alongthe line 3-3 with the first and second side plates in an un-weldedcondition;

FIG. 4 is a cross-section view of the vented brake rotor of FIG. 1 alongthe line 3-3 with the first and second side plates in a weldedcondition;

FIG. 5 is a cross-section view of a vented brake rotor with the firstand second side plates in an un-welded condition;

FIG. 6 is a cross-section view of the vented brake rotor of FIG. 5 withthe first and second side plates in a welded condition;

FIGS. 7A-7C are radial views illustrating exemplary vent portions ofvented brake rotors according to embodiments of the present application;

FIGS. 8 and 9 are flow charts describing exemplary methods of making avented brake rotor; and

FIG. 10 is a flow chart describing exemplary methods of making metalmatrix composite vehicle components.

DETAILED DESCRIPTION

As described herein, when one or more components are described as beingconnected, joined, affixed, coupled, attached, or otherwiseinterconnected, such interconnection may be direct as between thecomponents or may be indirect such as through the use of one or moreintermediary components. Also as described herein, reference to a“member,” “component,” or “portion” shall not be limited to a singlestructural member, component, or element but can include an assembly ofcomponents, members, or elements. Also as described herein, the terms“substantially” and “about” are defined as at least close to (andincludes) a given value or state (preferably within 10% of, morepreferably within 1% of, and most preferably within 0.1% of).

A MMC is generally made by incorporating a reinforcing material into ametal matrix, thereby enhancing the structure of the composite material.The MMC generally comprises two portions: a primarily inorganic metalportion and a porous structure made from other inorganic components,such as fused silicon carbide. For example, a MMC may be formed from aceramic preform that is infiltrated with a metal alloy, such asaluminum. Applicant has developed various MMCs and methods of makingMMCs, including aluminum MMCs. Examples of such MMCs and their relatedmethods are described in U.S. Pat. No. 9,429,202 (herein “the '202patent”) and U.S. Published Patent Application No. 2016/0108980 (i.e.,U.S. application Ser. No. 14/536,311; herein “the '311 application”),both of which are incorporated herein by reference in their entirety. Tothe extent the material incorporated by reference contradicts or isinconsistent with the present specification, the present specificationwill supersede any such material. The citation of any references hereinis not an admission that such references are prior art to the presentinvention.

Metal matrix composites embedded with a light weight metal, such as analuminum alloy, are useful in many industries, such as, for example,aerospace, automotive, heavy trucks, rail, defense, and others.Components made from light weight metal alloys that include localizedMMC portions may be used in any portion of a vehicle to reduce theweight of the component while maintaining or improving othercharacteristics of the material, such as, for example, wear resistance,durability, strength, thermal conductivity, or the like. Many differentvehicle components that include localized MMC portions (i.e., the MMCportion is restricted to a certain area of the component) may be formedand joined together using the methods described in the presentapplication. While forming rotating and rotationally symmetriccomponents having localized MMC portions—in particular, brake rotors—arediscussed in detail below, other non-rotating and non-rotationallysymmetric vehicle components, such as portions of a vehicle body,vehicle frame, or vehicle suspension can also be made using the methodsdescribed below.

The reduced weight of aluminum MMCs is particularly beneficial as areplacement for heavy components in vehicles, such as, for example,brake rotors that traditionally are made from cast iron. For example,the rear brake rotor of a 2015 Ford Fusion weighs approximately 11.5pounds, whereas an aluminum MMC brake drum weighs less than 5.3 lbs.This weight reduction improves the fuel economy of the car and—byreducing the unsprung weight—reduces vibration and noise, improveshandling, and increases the longevity of the vehicle. A brake rotorincorporating MMC materials into its wear surfaces can also haveimproved wear resistance, as described in the '311 application.

Rotors in disc brakes can be vented and non-vented. Vented brake rotorsmay be formed by machining the vents out of a solid piece of material,but doing so is time consuming and generates significant quantities ofscrap material. Additionally, some vent geometries are not possible tomachine from the exterior of the rotor.

Rather than machining the vents a vented brake rotor can also be cast asa single piece with the vents being shaped by portions of the mold. Thecast part is then machined to final dimensions. Cast parts can alsoincorporate MMC materials. Some previous attempts at developing MMCbrake rotors were not particularly successful due to the use of a stircasting technique. This technique does not produce a mixture having auniform distribution of the silicon carbide particles throughout thealuminum alloy.

For example, Duralcan (a stir casting technique used to combine siliconcarbide with aluminum) was used to produce a vented brake rotor for theChrysler Prowler, but there were significant distribution issues.Specifically, the silicon carbide was not uniformly distributed withinthe aluminum alloy resulting in some particles of silicon carbideprotruding from the surface of the rotor, in addition to otherinconsistencies. Another issue with Duralcan is that the silicon carbideparticles are distributed throughout the entire brake rotor.Consequently, machining the cast part requires special tools as siliconcarbide is interspersed throughout the aluminum. Various shortcomings ofthe Duralcan process are described in U.S. Pat. No. 6,547,850. The stircasting apparatus designed by Alcan Aluminum Company is described inU.S. Pat. No. 5,531,425.

Rather than mixing MMC materials throughout a vehicle component,applicant has shown—e.g., in the '202 patent and '311 application—thatcertain vehicle brake components can be formed with localized MMCportions. These MMC components are created by providing an MMC preformin the desired location before casting the part. The molten metal usedto cast the part infiltrates the ceramic preform to form a localized MMCportion of the final cast part. For example, a MMC portion can be formedon the wear surfaces of a brake rotor, as shown in FIG. 6A of the '311application.

When forming a component—such as a vehicle component—including a MMCportion, a ceramic preform is generally made first. The ceramic compoundused to form the ceramic preform may include a variety of components,such as, for example, ceramic particles, reinforcing fibers, starch,organic porous creating materials, low temperature binders, hightemperature binders (e.g., colloidal silica), and/or water.

An exemplary method of preparing a ceramic compound is disclosed below.First, the reinforcing fibers may be used in a detangling process. Thedry materials (e.g., ceramic particles, reinforcing fibers, starch, andorganic porous creating materials) are then added stepwise into aone-pot system and aggravated. The wet materials (e.g., low and hightemperature binders and water) may then be added slowly into the sameone-pot mixture, agitated, and then mixed under reduced pressure. Thishomogeneous one-pot mixture generally lacks voids and has randomlyoriented fibers and a malleable consistency. The mixture is then loadedinto a press and is compressed by male and female molds. Thiscompression molding technique provides uniform structure to the preform.Once the preform is molded, it is removed from the press and is slowlydried in a humid environment, supported by an absorptive liner. Oncewater is removed from preform, the preform and the absorbing liner areheated to extreme temperatures to remove organic materials and to fuseinorganic ceramic particles. Upon cooling, the ceramic preform ismachined to proper dimensions, the outer layer of skin is removed, andthe pores of preform are exposed.

Next, the preform is generally infiltrated with a metal that isdetermined based on the desired properties of the MMC component. This isdone through placing the heated preform in a die, pressurizing aluminuminto the mold cavity with sufficient pressure to impregnate the preformand to reach the desired casting pressure. The infiltration of thepreform may be facilitated through squeeze casting or slow injection diecasting. The cast part may then undergo heat treating and machining tothe desired characteristics and dimensions of the vehicle component.

Forming a vented brake rotor with MMC portions on both wear surfacesfrom two separate components provides various advantages. In particular,forming two separate components each having an MMC portion allows forcomplex vent geometries to be formed—e.g., those with complicated curvesor many different and non-linear flow paths. Additionally, alignment ofthe ceramic preforms in each of the two components can be maintainedmore easily as the ceramic preform is positioned only on one side of themold. Thus, a vented brake rotor may be formed by joining two sideplates together to enclose a plurality of vents. One or both side platesmay have vanes or posts machined into the mating surface so that ventsare formed when the two side plates are joined. In some embodiments, twoseparate infiltration die molding systems may be utilized to create eachhalf of the vented brake rotor, or a die system set with two separateddesigns could be utilized. After the two parts are removed from the dieand cooled the two halves can be machined to accurate dimensions.

According to the embodiments of the present application, the side platesmay be welded together. Each side plate is formed with an MMC portion onthe wear surface—e.g., the outer surface of the brake rotor—and may bemachined prior to being joined together. While the MMC portions can bedifficult to machine and weld, the inner mating surfaces are formed ofmetal (e.g., aluminum) with no MMC portions such that the metal withoutMMC portions can be machined and joined without the added complexityrequired by the MMC portions. These inner surfaces can also be machinedto form various vent geometries that would be difficult to achieve oreven impossible using conventional using single-piece casting methodsbecause of the difficulties associated with machining MMC materials asdiscussed above. Further, welding MMC materials is problematic becauseof embrittlement of the MMC material caused by increased temperaturesexperienced during welding or cracking caused during rotational welding(described below). Thus, machining and welding two halves of an MMCbrake rotor together is not viable with halves that are formed with MMCmaterial that is homogeneously distributed throughout the rotor.

Referring now to FIGS. 1 and 2, an exemplary vented brake rotor 100 isshown. The vented brake rotor 100 includes a vented area 110 formedbetween a first side plate 120 and a second side plate 130. The diameterof the brake rotor 100 is about 10 inches to about 15 inches. In someembodiments, the diameter of the brake rotor 100 is about 10 inches toabout 12 inches or about 11.8 inches. Each side plate 120, 130 includesan outer or wear surfaces 122, 132. The thickness of the brake rotor 100between the outer surfaces 122, 132 is about 0.6 to about 1.6 inches. Insome embodiments, the thickness of the brake rotor 100 is about 1.1inches. The brake rotor 100 is connected to and rotates with a wheel ofa vehicle through the hub 102. A brake caliper is actuated to squeezeagainst the wear surfaces 122, 132 to generate friction, therebygenerating a braking force and stopping the brake rotor 100 andconnected wheel from rotating.

The first side plate 120 is integrally formed with the hub 102. In someembodiments, the hub 102 is integrally formed with the second side plate130 and extends through an opening in the first side plate. The diameterof the hub 102 is about 4 inches to about 8 inches. In some embodiments,the diameter of the hub 102 is about 5.5 inches to about 6.5 inches, orabout 5.9 inches. In some embodiments, the hub 102 is a separatecomponent that is attached to the first or second side plate withfasteners or some other attachment means. The hub 102 is connected to avehicle axle and wheel (not shown) through bolt holes 104, though anysuitable means may be used to attach the hub 102 to the vehicle.

The vented area 110 is enclosed by the first and second side plates 120,130. A vent portion 112 extends between and joins the first and secondside plates 120, 130 to space apart the first and second side plates120, 130 to form a plurality of vents 114. The vents 114 have an inlet116 on the inner diameter of the vented area 110 and an outlet 118 onthe outer diameter of the vented area 110. Air is drawn into the inlets116 as the rotor 100 rotates. The air flows through the vents 114 and isexpelled from the outlets 118. Friction generated by the braking forceapplied to the rotor 100 by the caliper generates heat and causes therotor 100 to increase in temperature, which can weaken the material ofthe brake rotor 100. Air flowing through the vents 114 absorbs andcarries away heat generated by braking to produce a cooling effect,thereby allowing greater braking forces to be applied to the rotor 100without damaging the brake rotor 100 from overheating. The vent portion112 may be any structure that spaces apart the inner surfaces to formvents 114 in the vented area 110 between the first and second sideplates 120, 130, such as, for example, vanes, posts, or the like. Theillustrated first vented portion 112 includes straight vanes, though thevanes may be curved or segmented to alter the flow path of cooling areflowing through the vented area 110 of the spinning rotor during use.

Referring now to FIG. 3, a cross-sectional view of the brake rotor 100is shown with the first and second side plates 120, 130 in an un-weldedcondition—as separate components. The first and second side plates 120,130 each have inner surfaces 128, 138 that are welded together to formthe vented brake rotor 100. In the illustrated embodiment, the firstvent portion 112 extends from the first inner surface 128 to the secondinner surface 138. The distance between the first and second innersurfaces 128, 138 is about 0.3 inches to about 0.8 inches. In someembodiments, the distance between the first and second inner surfaces128, 138 is about 0.41 inches.

The cross-sectional view reveals MMC portions 124, 134 disposed at eachof the outer surfaces 122, 132 of the first and second side plates 120,130. The MMC portions 124, 134 extend toward the inner surfaces 128, 138from the outer surfaces 122, 132 to MMC boundaries 126, 136. The MMCboundaries 126, 136 are spaced apart from inner surfaces 128, 138 byfirst and second distances, respectively, that are less than a thicknessmeasured between the inner 128, 138 and outer surfaces 122, 132. In someembodiments, the first and second distances are about 0.03 inches toabout 0.10 inches. Thus, the inner surfaces 128, 138 and vent portion112 are entirely free from MMC components, thereby enabling the innersurfaces 128, 138 to be machined or welded without the use of specialtools needed to machine MMC materials. In some embodiments, the firstMMC portion 124 extends to the first inner surface 128 and the ventportion 112 is entirely free from MMC components. As shown in FIG. 4,the first and second side plates are welded together at a weld 140 thatmay be formed by the methods disclosed herein, such as, for example,rotational welding or fusion welding.

Rotational welding according to an embodiment of the present applicationis generally performed using machine such as a rotational welding lathe.Rotational welding involves pressing two metal surfaces of the sideplates together and rotating them relative to each other to scrape awaythe oxide layer and to increase the temperature of the material so thata metal bond (i.e., a weld) forms without reaching the melting point ofthe metal. To generate friction between the side plates, one of theplates may be rotated continuously while the other plate is fixed, orboth plates may be rotated continuously in opposite directions. In someembodiments, the rotation of the plates is discontinuous; that is, oneor both of the plates is rotated back and forth—first in one directionand then in the opposite direction—in rapid succession to generate heat.When the desired temperature is reached, the metal surfaces are pressedtogether to cure the weld.

In some embodiments, the components are rotated continuously at about500 to about 1,500 revolutions per minute, or at about 800 to about1,200 revolutions per minute. When pressing the components together tocure the weld the pressure applied ranges from about 100 to about 1,000pounds per square inch. The weld temperature reached at the innersurfaces of the rotating parts ranges from about 1,100 to about 1,250degrees Fahrenheit. In some embodiments, one or both of the inner orweld surfaces may be preheated—e.g., through resistance heating—to atemperature in a range of, for example, about 400 to about 900 degreesFahrenheit. However, the welding temperature, rotations per minute ofthe spinning component or components, the pressure applied to cure theweld, and the preheat temperature may all be varied based on thematerials used and surface area of the weld areas.

To weld the side plates 120, 130 together by rotational welding, theside plates 120, 130 are rotated around an axis of rotation 106 andpressed together as indicated by arrow 108 as shown in FIG. 3. Duringrotational welding, the side plates 120, 130 are moved together untilthe first vent portion 112 of the first inner surface 128 contacts thesecond inner surface 138. One or both of the side plates 120, 130 isthen rotated to generate friction between the side plates 120, 130. Whena sufficient temperature is reached, a plastic zone is created betweenthe first vent portion 112 and the second inner surface 138 and the twoside plates 120, 130 are pressed together to form the weld 140. Afterwelding, the rotor 100 can be machined to its final dimensions.

Fusion welding according to an embodiment of the present applicationgenerally involves heating one or both of the two side plates to bewelded and pressing them together to form a weld. In some embodiments,the side plates are placed in a grounded lathe such that an electricalcircuit is closed when the plates are pressed together. As electricalcurrent flows through the parts they are heated through resistanceheating. When the desired temperature is reached, the metal surfaces arepressed together to cure the weld.

In some embodiments, the weld temperature ranges from about 1,100 toabout 1,230 degrees Fahrenheit. The pressure applied to push the partstogether during fusion welding ranges from about 100 to about 300 poundsper square inch. One or both of the weld surfaces may be preheated—e.g.,through resistance heating—to about 230 degrees Fahrenheit before theplates are brought together. The current required to heat the partsvaries based on the pressure applied to press the components togetherand the contact area between the two parts. The welding temperature andthe pressure applied to form the weld, may all be varied based on thematerials used and surface area of the weld areas.

The welds joining two parts can be formed at the same time throughfusion welding or individually. The electrical current used to weld theparts together ranges from about 8,000 amperes to about 30,000 amperes,or about 8,500 amperes to about 12,500 amperes. The current may beapplied to all or multiple weld areas simultaneously or to individualweld areas. The current may be applied in one cycle that is held forabout 1 second to about 6 seconds. The current may also be applied inmultiple cycles—for example, up to about 40 cycles—that are each heldfor about 1 second to about 6 seconds. In some embodiments, the currentis applied in 6-7 cycles of about 1 second each, or 8-11 cycles of about2 second each, or 13-18 cycles of about 3 second each, or 23-30 cyclesof about 4-5 seconds each, or about 34-38 cycles of about 6 secondseach.

In some embodiments, the parts are brought into contact with each otherand then rotationally agitated, i.e., the plates are rapidly rotatedback and forth a few degrees in each direction to scrape away the oxidelayer before a current is applied and a weld is formed. The parts may berotated about 3 degrees in each direction, about 1 degree in eachdirection, or less than 1 degree in each direction. The small degree ofrotation during the fusion welding process allows for vent portions ofeach of the side plates to be substantially aligned and welded together.For example, vanes can be formed in each side plate and then weldedtogether to form the vented brake rotor. The parts may also be heated toa desired temperature above the melting point to burn away the oxidelayer through a high temperature burn off, such as, for example, atemperature ranging from about 1,250 to about 4,000 degrees Fahrenheit.

Referring now to FIG. 5, a cross-sectional view of a vented brake rotor200 is shown with first and second side plates 220, 230 in an un-weldedcondition—as separate components. Brake rotor 200 is similar to brakerotor 100, except that first and second vent portions 212, 213 extendfrom each of the first and second inner surfaces 228, 238, respectively.The first and second vent portions 212, 213 form vents 214 when weldedtogether.

Like brake rotor 100, the cross-sectional view of brake rotor 200reveals MMC portions 224, 234 disposed at each of the outer surfaces222, 232 of the first and second side plates 220, 230. The MMC portions224, 234 extend toward the inner surfaces 228, 238 from the outersurfaces 222, 232 to MMC boundaries 226, 236. The MMC boundaries 226,236 are spaced apart from inner surfaces 228, 238 by first and seconddistances, respectively, that are less than a thickness measured betweenthe inner 228, 238 and outer surfaces 222, 232. In some embodiments, thefirst and second distances are about 0.03 inches to about 0.10 inches.Thus, the inner surfaces 228, 238 and vent portions 212, 213 areentirely free from MMC components, thereby enabling the inner surfaces228, 238 and vent portions 212, 213 to be machined or welded without theuse of special tools needed to machine MMC materials. In someembodiments, the first and second MMC portions 224, 234 extend to thefirst and second inner surfaces 228, 238 and the vent portions 212, 213are entirely free from MMC components. As shown in FIG. 6, the first andsecond side plates are welded together at a weld 240 that may be formedby the methods disclosed herein, such as, for example, fusion welding.

To weld the side plates 220, 230 together by fusion welding, the sideplates 220, 230 are pressed together as indicated by arrow 208 as shownin FIG. 5. During fusion welding, the side plates 220, 230 are movedtogether until the first vent portion 212 of the first inner surface 228contacts the second vent portion 213 of second inner surface 238. Insome embodiments, the first and second vent portions 212, 213 overlap sothat the first vent portion 212 contacts the second inner surface 238and the second vent portion 213 contacts the first inner surface 228. Acurrent is then applied across the side plates 220, 230 to increase thetemperature of the contacting surfaces. When a sufficient temperature isreached, a plastic zone is created between the vent portions 212, 213and the two side plates 220, 230 are pressed together to form the weld240. After welding, the rotor 200 can be machined to its finaldimensions. The side plates 220, 230 may also be rotated back and fortharound axis 206 shown in FIGS. 5-6 prior to or during fusion welding.

Referring now to FIGS. 7A-7C, radial views are shown of exemplary firstand second vent portions of an exemplary vented brake rotor 700. Thevented brake rotor 700 includes a vented area 710 formed between a firstside plate 720 and a second side plate 730. Each side plate 720, 730includes outer surfaces 722, 732 and inner surfaces 728, 738.

Like brake rotors 100 and 200, the cross-sectional views of brake rotor700 reveals MMC portions 724, 734 disposed at each of the outer surfaces722, 732 of the first and second side plates 720, 730. The MMC portions724, 734 extend toward the inner surfaces 728, 738 from the outersurfaces 722, 732 to MMC boundaries 726, 736. The MMC boundaries 726,736 are spaced apart from inner surfaces 728, 738 by first and seconddistances, respectively, that are less than a thickness measured betweenthe inner 728, 738 and outer surfaces 722, 732. In some embodiments, thefirst and second distances are about 0.030 inches to about 0.100 inches.Thus, the inner surfaces 728, 738 and vent portions 712, 713 areentirely free from MMC components, thereby enabling the inner surfaces728, 738 and vent portions 712, 713 to be machined or welded without theuse of special tools needed to machine MMC materials.

As shown in FIG. 7A, the first side plate 720 includes a first ventportion 712 that extends from the first inner surface 728 to the secondinner surface 738. Like brake rotor 100, the second inner surface 738does not include a vent portion. The side plates 720, 730 of theembodiment shown in FIG. 7A can be welded together by any of the methodsdisclosed herein, such as, for example, rotational or fusion welding.

As shown in FIG. 7B, the first and second side plates 720, 730 includefirst and second vent portions 712, 713, respectively. Like brake rotor200, the first vent portion 712 extends from the first inner surface 728to meet the second vent portion 713 that extends from the second innersurface 738. The vent portions 712, 713 of the side plates 720, 730 ofthe embodiment shown in FIG. 7B are aligned during welding and thuscannot be welded by continuous rotational welding. However, the sideplates 720, 730 can be welded together by any of the other methodsdisclosed herein, such as, for example, discontinuous rotational weldingor fusion welding.

As shown in FIG. 7C, the first and second side plates 720, 730 includefirst and second vent portions 712, 713, respectively. The first andsecond vent portion 712, 713 overlap: the first vent portion 712 extendsfrom the first inner surface 728 to the second inner surface 738, andthe second vent portion 713 extends from the second inner surface 738 tothe first inner surface 728. The overlapping vent portions 712, 713 ofthe side plates 720, 730 of the embodiment shown in FIG. 7C prevent theside plates 720, 730 from being welded together by continuous rotationalwelding. However, the side plates 720, 730 can be welded together by anyof the other methods disclosed herein, such as, for example,discontinuous rotational welding or fusion welding.

Referring now to FIG. 8, a flow chart of an exemplary method 800 offorming a vented brake rotor is shown. The exemplary method 800includes: providing a first side plate having a first outer surface anda first inner surface, the first outer surface including a MMC portion,and the first inner surface having a first vent portion, at 802;providing a second side plate having a second outer surface and a secondinner surface, the second outer surface including a MMC portion, at 804;welding the first vent portion and the second inner surfaces of thefirst and second side plates together, at 806. In some embodiments, thesecond side plate includes a second vent portion. Exemplary method 800can be implemented to form the exemplary vented brake rotors 100, 200,and 700 described above, or another vented brake rotor.

Welding step 806 may include rotational welding performed by: placingthe first inner surface in contact with the second inner surface;rotating at least one of the first and second side plates at about 500to about 1,500 revolutions per minute; heating at least one of the firstand second surfaces to a weld temperature of about 1,100 to about 1,250degrees Fahrenheit; and pressing the first and second side platestogether at about 100 to about 1,000 pounds per square inch.Alternatively, welding step 806 may include fusion welding performed by:placing the first inner surface in contact with the second innersurface; heating at least one of the first and second surfaces viaresistance heating to a weld temperature of about 1,100 to about 1,250degrees Fahrenheit; and pressing the first and second side platestogether at about 100 to about 300 pounds per square inch. Welding step806 may also include preheating, rotational agitating, and/or hightemperature oxide burn off as described above.

Referring now to FIG. 9, a flow chart of an exemplary method 900 offorming a vented brake rotor is shown. The exemplary method 900includes: preparing a ceramic compound including reinforcing fibers andceramic particles, at 902; forming a first ceramic preform from theceramic compound, at 904; forming a first metal matrix composite brakecomponent having inner and outer surfaces—the inner surface having afirst vent portion—by infiltrating the first ceramic preform with moltenmetal, at 906; forming a second ceramic preform from the ceramiccompound, at 908; forming a second metal matrix composite brakecomponent having inner and outer surfaces by infiltrating the secondceramic preform with molten metal, at 910; and welding the first ventportion and the second inner surface together to form a vented brakerotor, at 912. In some embodiments, the second side plate includes asecond vent portion. Exemplary method 900 can be implemented to form theexemplary vented brake rotors 100, 200, and 700 described above, oranother vented brake rotor.

Welding step 912 may include rotational welding performed by: placingthe first inner surface in contact with the second inner surface;rotating at least one of the first and second side plates at about 500to about 1,500 revolutions per minute; heating at least one of the firstand second surfaces to a weld temperature of about 1,100 to about 1,250degrees Fahrenheit; and pressing the first and second side platestogether at about 100 to about 1,000 pounds per square inch.Alternatively, welding step 912 may include fusion welding performed by:placing the first inner surface in contact with the second innersurface; heating at least one of the first and second surfaces viaresistance heating to a weld temperature of about 1,100 to about 4,000degrees Fahrenheit; and pressing the first and second side platestogether at about 100 to about 300 pounds per square inch. Welding step912 may also include preheating, rotational agitating, and/or hightemperature oxide burn off as described above.

The methods described herein may be used to make a variety of vehicleand non-vehicle related components. This may include other vehiclecomponents (e.g., non-rotating and non-rotationally symmetric vehiclecomponents, such as portions of a vehicle body, vehicle frame, orvehicle suspension). For example, in certain embodiments, a firstvehicle component may include a MMC portion and a first metal portionthat is substantially free from MMC materials and a second vehiclecomponent may include a MMC portion and a second metal portion that issubstantially free from MMC materials such that it does not include anamount of MMC material that would affect the welding and machining ofthe metal portion. The first and second metal portions of the vehiclecomponents can be welded together by any of the methods disclosedherein, such as, for example, rotational or fusion welding.

Referring now to FIG. 10, a flow chart of an exemplary method 1000 offorming a metal matrix composite vehicle component is shown. Theexemplary method 1000 includes: providing a first vehicle componenthaving a first MMC portion and a first metal portion that issubstantially free from MMC materials, at 1002; providing a secondvehicle component having a second MMC portion and a second metal portionthat is substantially free from MMC materials, at 1004; and welding thefirst and second metal portions together to form the MMC vehiclecomponent, at 1006. Exemplary method 1000 can be implemented to form theexemplary vented brake rotors 100, 200, and 700 described above, or anyother vehicle components including localized MMC portions.

While various inventive aspects, concepts and features of thedisclosures may be described and illustrated herein as embodied incombination in the exemplary embodiments, these various aspects,concepts, and features may be used in many alternative embodiments,either individually or in various combinations and sub-combinationsthereof. Unless expressly excluded herein all such combinations andsub-combinations are intended to be within the scope of the presentapplication. Still further, while various alternative embodiments as tothe various aspects, concepts, and features of the disclosures—such asalternative materials, structures, configurations, methods, devices, andcomponents, alternatives as to form, fit, and function, and so on—may bedescribed herein, such descriptions are not intended to be a complete orexhaustive list of available alternative embodiments, whether presentlyknown or later developed. Those skilled in the art may readily adopt oneor more of the inventive aspects, concepts, or features into additionalembodiments and uses within the scope of the present application even ifsuch embodiments are not expressly disclosed herein.

Additionally, even though some features, concepts, or aspects of thedisclosures may be described herein as being a preferred arrangement ormethod, such description is not intended to suggest that such feature isrequired or necessary unless expressly so stated. Still further,exemplary or representative values and ranges may be included to assistin understanding the present application, however, such values andranges are not to be construed in a limiting sense and are intended tobe critical values or ranges only if so expressly stated.

Moreover, while various aspects, features and concepts may be expresslyidentified herein as being inventive or forming part of a disclosure,such identification is not intended to be exclusive, but rather theremay be inventive aspects, concepts, and features that are fullydescribed herein without being expressly identified as such or as partof a specific disclosure, the disclosures instead being set forth in theappended claims. Descriptions of exemplary methods or processes are notlimited to inclusion of all steps as being required in all cases, nor isthe order that the steps are presented to be construed as required ornecessary unless expressly so stated. The words used in the claims havetheir full ordinary meanings and are not limited in any way by thedescription of the embodiments in the specification.

What is claimed is:
 1. A method of making a metal matrix compositevented brake rotor, the method comprising: providing a first side platecomprising a first outer surface, a first inner surface having a firstvent portion, and a metal matrix composite portion extending from thefirst outer surface to a first distance from the inner surface that isless than a thickness measured between the first inner surface and firstouter surface; providing a second side plate comprising a second outersurface, a second inner surface, and a metal matrix composite portionextending from the second outer surface to a second distance from thesecond inner surface that is less than a thickness measured between thesecond inner surface and second outer surface; welding the first ventportion of the first inner surface to the second inner surface to formthe vented brake rotor, the vented brake rotor comprising a plurality ofvents formed by the first inner surface, the first vent portion, and thesecond inner surface.
 2. The method of claim 1, wherein the second innersurface has a second vent portion.
 3. The method of claim 2, wherein thestep of welding comprises welding the first vent portion of the firstinner surface to the second vent portion of the second inner surface. 4.The method of claim 2, wherein the step of welding comprises welding thefirst vent portion of the first inner surface to the second innersurface and welding the second vent portion of the second inner surfaceto the first inner surface.
 5. The method of claim 1, wherein the firstand second distances range from about 0.03 inches to about 0.10 inches.6. The method of claim 1, wherein the step of welding comprisesrotational welding.
 7. The method of claim 6, wherein rotational weldingcomprises: placing the first inner surface in contact with the secondinner surface; rotating at least one of the first and second side platesat about 500 to about 1,500 revolutions per minute; heating at least oneof the first and second surfaces to a weld temperature of about 1,100 toabout 1,250 degrees Fahrenheit; and pressing the first and second sideplates together at about 100 to about 1,000 pounds per square inch. 8.The method of claim 7, wherein rotational welding further comprisespre-heating at least one of the first and second surfaces to about 400to about 900 degrees Fahrenheit before placing the first inner surfacein contact with the second inner surface.
 9. The method of claim 1,wherein the step of welding comprises fusion welding.
 10. The method ofclaim 9, wherein fusion welding comprises: placing the first innersurface in contact with the second inner surface; heating at least oneof the first and second surfaces via resistance heating to a weldtemperature of about 1,100 to about 1,250 degrees Fahrenheit; pressingthe first and second side plates together at about 100 to about 300pounds per square inch;
 11. The method of claim 10, wherein fusionwelding further comprises pre-heating at least one of the first andsecond side plates to about 230 degrees Fahrenheit before placing thefirst inner surface in contact with the second inner surface.
 12. Themethod of claim 10, wherein fusion welding further comprises heating atleast one of the first and second side plates to about 1,200 to about4,000 degrees Fahrenheit before heating at least one of the first andsecond surfaces to a weld temperature.
 13. The method of claim 10,wherein fusion welding further comprises repeatedly rotating at leastone of the first and second side plates about 1 to about 3 degrees in afirst direction and then about 1 to about 3 degrees in a seconddirection.
 14. A method of making a metal matrix composite vented brakecomponent, the method comprising: preparing a ceramic compoundcomprising reinforcing fibers and ceramic particles; forming a firstceramic preform from the ceramic compound; forming a first metal matrixcomposite brake component by infiltrating the first ceramic preform withmolten metal, the first metal matrix composite brake componentcomprising a first outer surface, a first inner surface having a firstvent portion, and a metal matrix composite portion extending from thefirst outer surface to a first distance from the inner surface that isless than a thickness measured between the first inner surface and firstouter surface; forming a second ceramic preform from the ceramiccompound; forming a second metal matrix composite brake component byinfiltrating the second ceramic preform with molten metal, the secondmetal matrix composite brake component comprising a second outersurface, a second inner surface, and a metal matrix composite portionextending from the second outer surface to a second distance from thesecond inner surface that is less than a thickness measured between thesecond inner surface and second outer surface; welding the first ventportion of the first inner surface to the second inner surface to formthe vented brake rotor, the vented brake rotor comprising a plurality ofvents formed by the first inner surface, the first vent portion, and thesecond inner surface.
 15. The method of claim 14, wherein the ceramiccompound further comprises a fugitive porosity generating component,starch, a low temperature organic binder, a high temperature binder, andwater.
 16. The method of claim 14, wherein the second inner surface hasa second vent portion.
 17. The method of claim 16, wherein the step ofwelding comprises welding the first vent portion of the first innersurface to the second vent portion of the second inner surface.
 18. Themethod of claim 16, wherein the step of welding comprises welding thefirst vent portion of the first inner surface to the second innersurface and welding the second vent portion of the second inner surfaceto the first inner surface.
 19. The method of claim 14, wherein the stepof welding comprises rotational welding.
 20. The method of claim 14,wherein the step of welding comprises fusion welding.
 21. A vented metalmatrix composite brake rotor made according to the method of claim 1.22. A method of making a metal matrix composite vehicle component, themethod comprising: providing a first vehicle component having a firstmetal matrix composite portion and a first metal portion that issubstantially free from metal matrix composite material; providing asecond vehicle component having a second metal matrix composite portionand a second metal portion that is substantially free from metal matrixcomposite material; and welding the first and second metal portionstogether to form the metal matrix composite vehicle component.